Expression and activities of 11βHSD enzymes in the testes and reproductive tracts of sexually immature male pigs

Abstract

In light of studies implicating glucocorticoids in the control of testicular steroidogenesis and/or spermatogenesis, the objective of this study was to characterise the expression and activities of the 11β-hydroxysteroid dehydrogenase (11βHSD) enzymes in the testis and reproductive tract of the pre-pubertal pig. Although 11βHSD1 and 11βHSD2 mRNA transcripts and proteins were co-expressed in all regions of the reproductive tract, cortisol–cortisone inter-conversion was detectable in the testis, caput epididymidis and bulbourethral glands only. In homogenates of these 3 tissues, the apparent K m for NADP +- and NAD +-dependent 11β-dehydrogenase activities ranged between 152–883 and 47–479 nmol l −1, respectively. Irrespective of the pyridine nucleotide co-substrate, estimates of V max were consistently two orders of magnitude higher in the testis. Moreover, while, in each tissue, levels of cortisol oxidation were comparable in the presence of either NADP + or NAD +, maximal rates of NAD(P) +-dependent cortisol oxidation were up to 33-fold greater than the V max for NADPH-dependent reduction of cortisone. We conclude that in the testis, caput epididymidis and bulbourethral gland of the immature pig, NADP +- and NAD +-dependent 11βHSD enzymes catalyse net inactivation of cortisol, suggesting a physiological role for these enzymes in limiting local actions of glucocorticoids within these male reproductive tissues prior to puberty.